Centrifugally activated circuit changing mechanism



TTOPA/E Ks.

Dec. 12, 1950 c. s. PHILLIPS CENTRIFUGALLY ACTIVATED CIRCUIT CHANGING MECHANISM Filed July 5, 1947 aywgmg ciation with standard motor parts.

Patented Dec. 12, 1950' w rew/ CENTRIFUGALLY ACTIVATED CIRCUIT CHANGING MECHANISM Chester S. Phillips, St. Louis, Mo., assignor to The Emerson Electric Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application July 5, 1947, Serial No. 759,073

9 Claims. 1

This invention relates to improvements in centrifugally actuated circuit changing mechanism of the type particularly adapted to short circuit the windings of motors having a repulsion start and an induction operating characteristic.

An object of the invention is to provide a compact, quick, positive and uniformly acting mechanism for the purpose of converting from a repulsion starting operation to an induction running operation and the reverse, for embodiment in a repulsion-induction motor.

Another more specific object of the invention is to provide a mechanism of the type stated in which the action above mentioned is effected by making and breaking contact with all commutator bars of the armature suddenly and simultaneously when an adjustable predetermined motor speed has been attained, and thereby minimize sparking during the change from the one operation of the motor to the other.

A general object of the invention is to simplify mechanism of the character mentionedand to provide an eificient operating structure that is economical in construction and which may be installed with facility in motors of the type referred to. e

Other objects of the invention will appear from the following detailed description thereof taken in connection with the accompanying drawing, in which:

Fig. 1 is a vertical longitudinal section taken substantially on the line l-l of Fig. 2;

Fig. 2 is a vertical cross section taken substantially on the line 22 of Fig. 1;

Fig. 3 is a fragmentary plan view, showing a part of the commutator and of the circuit-change mechanism;

Fig. 4 is a fragmentary longitudinal sectional view showing a part of the commutator and of the circuit-change mechanism, with the latter in short-circuiting position; V

Fig. 5 is an enlarged vertical fragmentary section of the retaining discs for the short-circuiting segments, one of the segments being shown in side elevation;

Fig. 6 is an isometric view of one of the weight units and two of the associated links; and

Fig. '7 is an isometric view of one of the shortcircuiting segments removed from the assembly.

In the embodiment of the invention selected r for illustration, the structure is shown in asso It will be understood that the motor windings are such that, during the starting period, the motor is designed to operate with a repulsion characteristic by current shunted through brushes (not shown),

which contact the horizontal surface of the commutator bars; and that, by short circuiting the vertical faces of the commutator bars, the motor winding permits the conversion from repulsion operation to induction operation, as will be readily understood.

By reference, therefore, to the drawing, it will be understood that a motor of this type includes a motor shaft l0 upon which a. commutator ll having an annular series of commutator bars I2 is mounted. The bars are assembled as usual in an annular series to provide a horizontal peripheral surface which the brushes contact to complete the circuit during the repulsion operation of the motor. The bars also form an annulus at the inner end thereof providing a vertical contact surface which, in cooperation with movable contacting segments, operate to short circuit the commutator bars and thereby convert the motor for an induction operation during the running period of the motor.

It will be understood that the commutator is affixed to the motor shaft, as shown by a pin 14 that passes through the shaft and the hub of the commutator shell. These elements together comprise the armature assembly of the motor and are standard, as will be well recognized. They are illustrated merelyv for the purpose of disclosing the manner in which the mechanism of the present invention is assembled and associated there with.

The mechanism of the present invention includes a sleeve I5 that is fitted over the shaft ID. A contact assembly carrier, comprising an inner annular disc [6 and an outer annular disc I1, is mounted over the sleeve 15. The disc H5, "at its periphery, is formed to provide a U-shaped recess i8 and the disc H is extended beyond the periphcry of the disc [6, forming a pocket in which an annular series of contact segments 28 are mounted. The contact segments are in the form best shown in Figs. 5 and '7, and include an upper rectangular section with an integral tail piece 2| providing a recess l9 into which the peripheral margin or flange 5B of the plate 16 extends. The

outer walls of the members 20 are held in position b the marginal extremity of the disc [1.

The contact segments are assembled in an annular series in their carrier and support, and the two discs iii and Il are spot welded, as at a Fig. 5), or otherwise secured at their matching parallel faces, so that the annular series of contact segments is free to move circumferentially. outwardly from the outer face of the disc ll is an annular plate 22 likewise fitting over the .s evflfi and assembled in abutment with the 3 outer face of the disc ll. The plate 22 is provided with six pairs of ears 23, arranged in groups of two pairs, one radially outside of the other, and the groups spaced circumferentially at angles of 120. Each group of these ears may be dieformed from the plate, leaving an opening 28 on the edgeson which the ears appear.

The plate 22 is provided with an axial hub 24, which is mounted over the external wall of the sleeve l5 and is longitudinally slidable thereon. The diameters of the axial openings in the discs l6 and ll are slightly in excess of the external diameter of the hub 24, and the discs, therefore, mount over and surround the .outer periphery of said hub 24.

A second annular plate 25 having a hub .26 ,is likewise mounted over and carried by the sleeve I5. The hub flange 26 of the plate 25 is afilxed to the sleeve It by welding, or by other suitable securing means, and, therefore, is not longi tudinally movable in respect .to .the sleeve. Fur thermore, the sleeve l5 and the hub 26 are fixedly secured to the shaft 10 by a pin 40 that extends through these members.

The plate is provided with six pairs of ears 2?? that extend forwardly from the front face thereof, and are arranged in three groups of two pairs .of each group, in the same manner in respect of the plate 25 as the cars 23 are arrangedin respect ,of the plate 22, each group of four ears being disposed at the edges of an p ning 28.

Three weight .assemblies are designed to be pivotall mounted between the .plate 22 and the plate .25. The weight assembly construction is illustrated particularly in Fig. 6 from which it willbe understood that each includes a rectangular weight member 33 pivotally connected to a pairof toggle linkaeach linkbeingin theforin as shown in Fig. '6 and each including a right and left linkbar 3.! ,spacedapart and transversely connected bya web 32.

.A ,pin .33 constitutes a common pivot for the inner .ends of thellinks .31 and the weight member 30.,said pinpass'ing through the inner extremities of said link bars .and transversely through an Upper section of the weight member. The outer extremities of each of the link bars 3| are connected, respectively, with the ears 23 and the ears '2! by pivot pins 34, the outer ends of the forward ,pains of links extending through the openings 25?, as best .illustratedinl figs. ,1 and 4 .of the drawing. ,There are two pairs of the links connected with radial spacing, to each Weight memberet, to maintain the .weightsradial during their movement.

The vertical innerfaces of the series oficontact segments 2B are normally retracted from the vertical faces .of the commutator bars I2 by meansof ,anexpansionspringfiii coiled about the shaft Ill and bearingat its outer extremity .against a flanged .collartfi encompassing the shaft 10. The 10111161 face of the flange of said collarabuts against the face of the hub of the commutator shell. The spring, at its opposite end, bears againstthe axial margin of the disc 16 andoverlies the outer margin of the hub flange .24 of the annular plate 22.

The mechanical advantage of the toggle links increases as the weights move outwardly; and also, as the weights move outwardly, their rotative speed increases. Consequently, when .sufficient speedis attained to start the weights outwardly,

they. continue to movewithincreasing centrifugal speed, and close the short-.circuitins segments In their outer positions, the weights act with maximum force, and the toggle links act with maximum advantage, so that the short-circuiting segments are held forcibly against the commutator bars. The toggle links are short of dead center in the outer position, but are preferably near dead center.

When the speed decreases to a point where the centrifugal force of the weights acting throughthe spread toggle links is no longer able to overcome the spring 35, the spring will collapse the toggle links, forcing the weights in. As theweights move inward from operating position, their centrifugal force and the mechanical advantage .of the links decreases rapidly, and the weights move in rapidly, giving a snap-action break of the short-circuiting segments from the commutator bars.

.Since the protracted movement is due to the weighted toggle links equi-circumferentially spaced, and the toggle links are arranged in parallel pairs in each group, the two plates -.or discs ii and 25 are maintained parallel, overcomin any lag in an individual radial movement of any one .of the weights. Hence the circumferential contact between the contact segments and the vertical faces ,of the commutator bars is uniformly and substantially simultaneously effected.

This mechanism isreadily made and assembled in place. Theshort-circuiter sub-assemblies are formed by spot welding together the two-discs l6 and ll with their segments 20 between them. The centrifugal weight assemblies are ,preassembled by weldin the plate .25 to the sleeve i5, sliding the plate '22 over the sleeve, pinning the links in place, and pinning the several weights to the links. v

The retainer ring '35 is slid onto the shaft I0 into abutting relationship with the commutator, as shown. The coil spring 35is then put over the shaft. The short-circuiter sub-assembly is put over the shaft against the spring. The weight sub-assembly on the sleeve i5 is fitted over the shaft, and finally the pin 40 ,is secured in place to hold all of the parts together.

The construction, as ap ears from the foregoing, leads to convenient and inexpensive nanufacture,. sub-assembly and final assembly.

From the foregoing description, it .willbe understood that the invention fully accomplishes the purposes hereinbefore set out, and that, while I have illustrated a specific embodiment and have particularly described the details of the construction, it is not to be understood that the in- .vention is limited except as defined by the claims.

What .is claimed is:

1. ,In a centrifugal actuator for mounting on a. rotary shaft, a first member mounted onthe shaft for rotation therewith, a second member mounted for axial movement relatively to the shaft, .a centrifugal weight, .a pair of parallel links pivotally connecting the weight with the second member, the links of the pair being disposed at different distances from the axisof the shaft to determine the path of movement of the weight relatively to the second member, and link means pivoting the weight to the first member.

2. ,Ina centrifugal actuator for mounting on a rotary shaft, a first member mounted on the shaft for rotation therewith, a second member mounted for axial movement relatively to the shaft, a centrifugal weight, a pair of parallel links pivotally vconnecting the weight with the second member, and link means pivoting the weight to the first member, said link means likewise comprising a, pair of parallel links pivoted to the weight and to the first member, the links of each pair being at different distances from the axis of the shaft to fix the path of movement of the weight relatively to the second member.

3. In a centrifugal actuator for mounting on a rotary shaft, a first member mounted on the shaft for rotation therewith, a second member mounted for axial movement relatively to the shaft, a centrifugal weight, a pair of parallel links pivotally connecting the weight with the second member, the links being disposed in a plane radial to the axis of the shaft, and link means pivoting the weight to the first member, said link means likewise comprising apair of parallel links pivoted to the weight and to the first member, the two pairs of links having common pivots on the weight, there being one pivot connecting the two radially inward links, and one pivot connecting the two radially outward links with the weight.

4. In a centrifugal actuator for mounting on a rotary shaft, a first member mounted on the shaft for rotation therewith, a second member mounted for axial movement relatively to the shaft, a plurality of at least three centrifugal weights arranged in spaced relation around the shaft, a pair of parallel links for each weight, the links of each pair being arranged at different distances from the axis of. the shaft, and each pivoted to the weight and to the second member, and link means connecting each of the weights pivotally to the first member.

5. In a centrifugal actuator for mounting on a rotary shaft, a first member mounted on the shaft for rotation therewith, a second member mounted for axial movement relatively to the shaft, a plurality ofat least three centrifugal weights arranged in spaced relation around the shaft, a pair of parallel links for each weight, the links of the pair being arranged at different distances from the axis of the shaft, and each pivoted to the weight and to the second member, and link means connecting each of the weights pivotally to the first member, said link means comprising a pair of parallel links for each weight, pivoted thereto and to the first member, the links of the latter pair being likewise arranged at different distances from the axis of the shaft.

6. In a centrifugal actuator for mounting on a rotary shaft, a first member mounted on the shaft for rotation therewith, a second member mounted for axial movement relatively to the shaft, a centrifugal weight, a pair of parallel links pivotally connecting the weight with the second member, a second pair of parallel links pivoting the weight to the first member, said second member comprising a disc-like element, a short-circuiting device including a disc-like assembly, and means yieldably urging the short circuiting device toward the second member.

7. In a centrifugal actuator for mounting on a rotary shaft, a first member mounted on the shaft for rotation therewith, a second member mounted for axial movement relatively to the shaft, a centrifugal weight, a pair of parallel links pivotally connecting the weight with the second member, the links being disposed at different distances from the axis of the shaft, and link means pivoting the weight to the first memher, said link means likewise comprising a pair of parallel links pivoted to the weight and to the first member, the links of the latter pair being at different distances from the axis of the shaft, the links being arranged in a toggle manner wherein, when the weight is toward the axis, the links between the weight and the second member extend from the weight angularly outward, and when the weight is moved outwardly, the links approach parallelism to the said axis, an axially movable actuated device, yieldalcle means urging it axially toward the second member, said actuated device being adapted to be moved by the centrifugal movement of the weights to a position short of that in which the links are parallel to the axis of rotation.

8. In a centrifugal short-circuiting mechanism for an electric motor having a shaft and commutator elements having contact faces disposed annularly about the shaft, a short-circuiting device sub-assembly including a pair of discs having holes to receive the shaft, and attached together face to face, said discs being shaped to provide a peripheral groove with a retaining edge, a plurality of commutator segments in the groove and retained by the edge, but peripherally slidable in the groove, a spring surrounding the shaft and engaging the said sub-assembly and arranged to urge the sub-assembly away from the commutator elements, a centrifugal actuator subassembly including a first and a second disc-like actuator member having shaft receiving holes, a sleeve fixed to the first actuator member, 3, plurality of centrifugal weights spaced about the axis of the shaft, link means pivoting the weights to the two actuator members, this actuator subassembly being fittable over the shaft with the second actuator member engaging the short-circuiting device sub-assembly opposite the spring, and means attaching the first actuator member to the shaft.

9. In a centrifugal actuator, a sleeve adapted to fit over a shaft, a first radial member attached to the sleeve and extending outwardly therefrom to provide at least three points of connection spaced around the shaft, a second radial member slidably mounted over the sleeve, and extending outwardly to provide corresponding points of connection, at least three weights between the two members, two pairs of links for each weight, one pair being pivoted to the weight and the first member, the other pair being pivoted to the weight and the second member, the links of each pair, with the weight and the respective member, providing a parallelogram linkage that holds the second member in parallelism to the first member as the weights move radially.

CHESTER S. PHILLIPS.

1 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 809,560 Graham Jan. 9, 1906 1,194,103 Welch Aug. 8, 1916 1,214,286 Douglas Jan. 30, 1917 1,557,052 Himes Oct. 13, 1925 1,927,597 Roth Sept. 19, 1933 2,142,403 McCullouch Jan. 3, 1939 2,226,188 Wittel Dec. 24, 1940 FOREIGN PATENTS Number Country Date 167,554 Switzerland May 16, 1934 557,588 Germany Aug. 25, 1932 

